Recognize nested logical operations.

lib/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class SsaCodeGeneratorTask extends CompilerTask {
   final JavaScriptBackend backend;
   SsaCodeGeneratorTask(JavaScriptBackend backend)
       : this.backend = backend,
         super(backend.compiler);
   String get name() => 'SSA code generator';
@@ skipping 1706 matching lines @@
       endExpression(JSPrecedence.PREFIX_PRECEDENCE);
     }
   }
 
   visitParameterValue(HParameterValue node) {
     assert(isGenerateAtUseSite(node));
     buffer.add(variableNames.getName(node));
   }
 
   visitPhi(HPhi node) {
-    HBasicBlock ifBlock = node.block.predecessors[0].predecessors[0];
     // This method is only called for phis that are generated at use
     // site. A phi can be generated at use site only if it is the
     // result of a logical operation.
+    HBasicBlock ifBlock = node.block.dominator;
     assert(logicalOperations.contains(ifBlock.last));
     HInstruction input = ifBlock.last.inputs[0];
     if (input.isConstantFalse()) {
       use(node.inputs[1], expectedPrecedence);
     } else if (input.isConstantTrue()) {
       use(node.inputs[0], expectedPrecedence);
     } else {
       String operation = node.inputs[1].isConstantFalse() ? '&&' : '||';
       JSBinaryOperatorPrecedence operatorPrecedence =
           JSPrecedence.binary[operation];
@@ skipping 932 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }